Well, I also expected an answer from how you saw the functioning of these powers.
Hey @Qwertyjadhfalhwjdgawlaiwb The idea was that the character have one of them, not all of them, that's cheating. HAHAHAHAHAHAHA
Well, I'll talk how I would do it at the same time how I see such powers.
For Scientiapotence: It would not be just a character, but an entire civilization, they would be responsible for the control, functioning and maintenance of all infinite multiverse, just interfering when necessary. They would be beings of pure consciousness, with such small micro-technology that it would have become part of the entirety existence, they would even have merged their consciences with their own technology, becoming one, and there is no further distinction between their existence and their technology. This is how I imagine it would be a user of such power, their own existence and their technology would have merged and it would be one thing, not being an external thing that they need to use, but being themselves.
For Arcanepotence: This would be simpler, a being that has infinite magic, in which he has already discovered all the possible spells, and if there is any magic he does not know, he only learns from looking at magic and understands how it works, probably even being an unlimited magical energy being, without having a physical body, becoming a magic entity. Perhaps even becoming the source of all magic, from where the lower beings take off their powers.
For Almighty Mind: Perhaps someone in which he was able to master all kinds of mental powers and became an eternal existence that exists only by consciousness, with a mind that understands everything in the universe and capable of using it to do everything, someone with unlimited knowledge, almost equal to a Scientiapotence user, but without the technology, besides, It would be all very similar.
For Autopotence: Eh, this one I don't know how I would do, this I really didn't understand how the functioning of its powers differ from others.